Continuity mistake: When Stewie jumps off the side of the hot air balloon, he has no rope attached to his ankle. Next shot they show him hanging from the hot air balloon from a rope tied to his ankle.
Character mistake: In the cutaway gag involving George and Lorraine McFly from "Back To The Future" Lorraine says she hasn't seen Marty from high school since prom. George, Lorraine and Marty all attended the Enchantment Under the Sea dance in November 1955, not the prom, which is usually held in the spring.
Continuity mistake: At the Founding Father Restaurant, Stewie is drawing on a treasure map in red crayon and Peter takes it. In the next scene, where Peter shows the map to Quagmire and Joe at the Clam, the red crayon mark is no longer there.
Chosen answer: It's a real song called "Elvira". Originally by Dallas Fraizer in '66, however, this version seems to be the Oak Ridge Boys cover version. However, the mega lesbians skip the verse and just sing the chorus after the opening line.
Bishop73